Cause

This is due to a known issue that happens while processing a line in the custom unattend.xml, which leads to task sequence variable values not being properly set. As a result, in this example, the desired default language was not properly set.

Resolution

To prevent his from happening, remove the following line from the unattend.xml:<cpi:offlineImage cpi:source="wim:path-to-windows-image.wim#Windows" xmlns:cpi="urn:schemas-microsoft-com:cpi" />

Removing the above tag has no impact on the deployment.

More Information

The reference to the offline image is added by default by WSIM to track which Windows Image was used for creating the unattend.xml file.